China tried to electronically jam U.S. drone flights over the South China Sea in a bid to thwart spying on disputed island military construction, U.S. officials said. Global Hawk long-range surveillance drones were targeted by the jamming in at least one incident near the disputed Spratly Islands, where China is building military facilities on Fiery Cross Reef.

China’s military plans to produce nearly 42,000 land-based and sea-based unmanned weapons and sensor platforms as part of its continuing, large-scale military buildup, the Pentagon’s annual report on the People’s Liberation Army (PLA) disclosed Friday.

China currently operates several armed and unarmed drone aircraft and is developing long-range range unmanned aerial vehicles (UAVs) for both intelligence gathering and bombing attacks.

Visitors of the New York Times website—a go-to for criticism of the Guantanamo Bay detention camp and all enhanced interrogation techniques—on Friday will find that it has a far more nuanced take on President Barack Obama’s use of drone strikes in the Middle East that resulted in a dead American hostage.